WO2024001124A1

WO2024001124A1 - Isolated ac-dc converter, charging device, and power supply system

Info

Publication number: WO2024001124A1
Application number: PCT/CN2022/142477
Authority: WO
Inventors: 庄加才; 徐君
Original assignee: 阳光电源股份有限公司
Priority date: 2022-06-28
Filing date: 2022-12-27
Publication date: 2024-01-04
Also published as: CN114928241A

Abstract

The present application discloses an isolated AC-DC converter, a charging device, and a power supply system. The isolated AC-DC converter comprises: a PFC filter, wherein an input end of the PFC filter is connected to an alternating current; a PFC circuit, wherein an input end of the PFC circuit is connected to an output end of the PFC filter, and an output end of the PFC circuit is connected to an input end of a DC-DC circuit; and the DC-DC circuit, comprising a transformer, wherein the transformer comprises: a primary winding, a secondary winding, and a first shielding layer; the first shielding layer is arranged between the primary winding and the secondary winding; the first shielding layer is connected to the PFC filter for preventing an interference signal from being transmitted to the secondary winding. In order to prevent an interference source from being transmitted to the secondary winding by means of the primary winding, the interference signal of the primary winding of the transformer is transmitted back to the PFC filter by means of the first shielding layer to form a common-mode loop for preventing the interference signal from being transmitted to the secondary winding. According to the solution, an EMC filter does not need to be additionally arranged, a shielding layer is additionally arranged, the implementation is easy, and the size and the volume are not greatly increased.

Description

An isolated ACDC converter, charging equipment and power supply system

This application requests the priority of the Chinese patent application with the application number 202210743957. The entire contents of which are incorporated herein by reference.

Technical field

This application relates to the field of power electronics technology, specifically to an isolated ACDC converter, charging equipment and power supply system.

Background technique

At present, the isolated ACDC converter adopts a two-stage architecture. The front stage is a PFC circuit with rectification function, and the rear stage is an isolated DCDC circuit. The isolated DCDC circuit includes a transformer.

In actual applications, the primary winding and secondary winding of the transformer may have capacitors connected in parallel, or there may be a coupling capacitor between the primary winding and the secondary winding of the transformer. The interference source generated by the PFC circuit can be transmitted to the secondary winding of the transformer through the capacitor, and then A large common-mode loop channel is formed, causing the EMC performance of the isolated ACDC converter to degrade.

In order to improve EMC performance, add an AC EMC filter before the PFC circuit to increase the common mode impedance. However, in order to meet EMC standards, the PFC circuit needs to increase the filter impedance. When the output needs to pass the EMC standard, the DC output also needs to add a high-impedance filter unit, as shown in Figure 2. High-impedance EMC filter units will inevitably bring disadvantages such as increased cost, increased size and weight.

Contents of the invention

In order to solve the above technical problems, this application provides an isolated ACDC converter, charging equipment and power supply system, which can improve EMC performance without causing an increase in the size and weight of the converter.

This application provides an isolated ACDC converter, including: PFC filter, PFC circuit and DCDC circuit;

The input end of the PFC filter is used to connect to alternating current;

The input terminal of the PFC circuit is connected to the output terminal of the PFC filter;

The output terminal of the PFC circuit is connected to the input terminal of the DCDC circuit;

The DCDC circuit includes a transformer, which includes: primary winding, secondary winding and first shielding layer;

The first shielding layer is arranged between the primary winding and the secondary winding. The first shielding layer is connected to the PFC filter to form a common mode loop to block interference signals from being transmitted to the secondary winding.

Preferably, the PFC filter includes a filter capacitor and a filter inductor;

The input end of the PFC circuit is connected to the first end of the filter inductor, the second end of the filter inductor is connected to the first end of the filter capacitor, and the second end of the filter capacitor is connected to the first shielding layer.

Preferably, the PFC filter includes a filter capacitor and a filter inductor;

The input end of the PFC circuit is connected to the first end of the filter inductor, the second end of the filter inductor is connected to the first end of the filter capacitor, and the second end of the filter inductor is connected to the first shielding layer.

Preferably, it also includes: a second shielding layer;

The second shielding layer is arranged between the primary winding and the first shielding layer. The second shielding layer is connected to the DC bus of the DCDC circuit. The second shielding layer is used to suppress the interference signal of the switch tube of the primary winding of the DCDC circuit.

Preferably, it also includes: a third shielding layer;

The third shielding layer is disposed between the secondary winding and the first shielding layer, and the third shielding layer is connected to one end of the output capacitor of the DCDC circuit.

Preferably, the first shielding layer is a copper foil located between the primary winding and the secondary winding, and one end of the copper foil is connected to the PFC filter through an electrical connection wire.

Preferably, the isolated ACDC converter is a three-phase converter or a single-phase converter.

Preferably, the input end of the PFC circuit is used to connect three-phase alternating current, and the PFC circuit includes a three-level circuit or a two-level circuit;

The DCDC circuit includes a DCAC inverter bridge, a transformer and an ACDC rectifier bridge; the input end of the DCAC inverter bridge is connected to the output end of the PFC circuit, the primary winding of the transformer is connected to the output end of the DCAC inverter bridge, and the secondary winding of the transformer is connected to the ACDC rectifier input of the bridge.

This application also provides a charging device, including the isolated ACDC converter introduced above; and also includes: a controller;

The controller is used to control the output end of the isolated ACDC converter to charge the electrical equipment.

This application also provides a power supply system, which includes the isolated ACDC converter introduced above; and also includes: a controller; the controller is used to control the output end of the isolated ACDC converter to supply power to electrical equipment.

It can be seen that this application has the following beneficial effects:

The isolated ACDC converter provided by this application includes: PFC filter, PFC circuit and DCDC circuit; the input end of the PFC filter is used to connect to the alternating current; the input end of the PFC circuit is connected to the output end of the PFC filter; the output end of the PFC circuit Connect the input end of the DCDC circuit; the DCDC circuit includes a transformer, and the transformer includes: a primary winding, a secondary winding and a first shielding layer; the first shielding layer is arranged between the primary winding and the secondary winding, and the first shielding layer is connected to the PFC The filter forms a common mode loop, reduces the common mode current in the PFC circuit caused by the coupling capacitance between the primary winding and the secondary winding of the transformer, and prevents interference signals from being transmitted to the secondary winding. This application does not specifically limit the specific location where the first shielding layer is connected to the PFC filter. For example, it can be connected to one end of the filter capacitor in the PFC filter, or it can be directly connected to a phase line of the AC input. Since the PFC filter generates interference sources, in this application, in order to prevent the interference sources from being transmitted to the secondary winding through the primary winding of the transformer, the interference signal from the primary winding of the transformer is transmitted back to the PFC filter through the first shielding layer, thereby forming a common mode loop to block interference signals from being transmitted to the secondary winding. This solution does not require an additional EMC filter and only adds a shielding layer. It is easy to implement, and the size and volume will not increase too much.

Description of drawings

Figure 1 is a schematic diagram of an isolated ACDC converter;

Figure 2 is a schematic diagram of an isolated ACDC converter with EMC filter;

Figure 3 is a schematic diagram of an isolated ACDC converter provided by an embodiment of the present application;

Figure 4 is a circuit diagram of a specific isolated ACDC converter of Figure 3;

Figure 5 is an equivalent circuit diagram provided by an embodiment of the present application;

Figure 6 is a schematic diagram of another isolated ACDC converter provided by an embodiment of the present application;

Figure 7 is a schematic diagram of yet another isolated ACDC converter provided by an embodiment of the present application;

Figure 8 is a schematic diagram of another isolated ACDC converter provided by an embodiment of the present application;

Figure 9 is a schematic diagram of another isolated ACDC converter provided by an embodiment of the present application;

Figure 10 is a schematic diagram of a PFC circuit provided by an embodiment of the present application;

Figure 11 is a schematic diagram of another PFC circuit provided by an embodiment of the present application;

Figure 12 is a schematic diagram of another PFC circuit provided by an embodiment of the present application;

Figure 13 is a schematic diagram of a charging device provided by an embodiment of the present application;

Figure 14 is a schematic diagram of a power supply system provided by an embodiment of the present application.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions provided by this application, specific application scenarios are first introduced below.

The isolated ACDC converter provided by the embodiment of the present application can be used in many occasions, such as communication power supply, and can be used to supply power to the computer room. It can also be used in vehicle chargers and charging piles. This application does not specifically limit the load type corresponding to the isolated ACDC converter.

The isolated ACDC converter provided by the embodiment of the present application may be three-phase or single-phase. The following is an example of an introduction where the isolated ACDC converter is a three-phase converter.

Refer to Figure 1, which is a schematic diagram of an isolated ACDC converter.

The isolated ACDC converter provided by the embodiment of the present application includes two stages. The first stage is a PFC circuit 100 and the second stage is a DCDC circuit 200. The DCDC circuit 200 is an isolated type, that is, it includes a transformer T and the primary winding of the transformer T. The DCAC inverter bridge formed by the switching tube is connected, and the secondary winding of the transformer T is connected to the ACDC rectifier bridge formed by the switching tube.

Since the interference source generated by the PFC circuit may be transmitted to the secondary winding of the transformer T through the capacitance or coupling capacitance of the transformer T, causing common mode interference and causing the EMC performance of the entire isolated ACDC converter to decline, generally in order to improve the EMC performance, as shown in the figure In the isolated ACDC converter shown in 2, before the PFC circuit 100, an AC EMC filter 400 is generally added to the input end of the PFC filter 300, and sometimes a DC EMC filter 500 is added to the output end of the DCDC circuit 200. Since EMC filters generally include inductors, the entire circuit will be larger in size, weight and cost. The PFC filter 300 is a differential mode filter, mainly for filtering out differential mode interference.

The isolated ACDC converter provided by the embodiment of the present application does not add an EMC filter, but adds a shielding layer between the primary winding and the secondary winding of the transformer to shield the interference source of the PFC circuit and prevent interference signals from being transmitted through the transformer. The circuit to the secondary winding of the transformer, and the secondary winding, affects the load.

The isolated ACDC converter provided by the embodiment of the present application will be introduced in detail below with reference to the accompanying drawings.

Refer to Figure 3, which is a schematic diagram of an isolated ACDC converter provided by an embodiment of the present application.

The isolated ACDC converter provided in this embodiment includes: PFC filter 300, PFC circuit 100 and DCDC circuit 200;

The input end of the PFC filter 300 is used to connect to alternating current;

The input terminal of the PFC circuit 100 is connected to the output terminal of the PFC filter 300;

The output terminal of the PFC circuit 100 is connected to the input terminal of the DCDC circuit 200;

The DCDC circuit 200 includes a transformer T, and the transformer T includes: a primary winding, a secondary winding and a first shielding layer 10;

The embodiments of the present application do not specifically limit the specific implementation form of the rectifier circuit and the inverter circuit inside the DCDC circuit 200, which may be a full bridge, a half bridge, etc. In this embodiment, the DCDC circuit 200 including the DCAC inverter 201 and the ACDC rectifier 202 is specifically introduced as an example.

The first shielding layer 10 is disposed between the primary winding and the secondary winding. The first shielding layer 10 is connected to the PFC filter 300 to form a common mode loop and block interference signals from being transmitted to the secondary winding.

The embodiment of the present application does not specifically limit the specific material of the first shielding layer 10. For example, it can be a material with conductive properties such as copper foil.

The embodiment of the present application does not specifically limit the specific location where the first shielding layer 10 is connected to the PFC filter 300. For example, it may be connected to one end of the filter capacitor in the PFC filter 300. Since the PFC filter 300 generates an interference source, in this application, in order to prevent the interference source from being transmitted to the secondary winding through the primary winding of the transformer T, the interference signal from the primary winding of the transformer T is transmitted back to the PFC filter through the first shielding layer 10 300, thereby forming a common mode loop and blocking interference signals from being transmitted to the secondary winding. This application does not specifically limit the specific location where the first shielding layer is connected to the PFC filter. For example, it can be connected to one end of the filter capacitor in the PFC filter, or it can be directly connected to a phase line of the AC input. This solution does not require an additional EMC filter, but only adds a shielding layer, which is easy to implement, and the size and volume will not increase too much.

The secondary winding of the transformer T is connected to the ACDC rectifier 202, and the secondary winding of the ACDC rectifier bridge 202 outputs direct current to power the load.

The isolated ACDC converter shown in Figure 4 is a specific implementation of Figure 3.

Figure 4 takes a three-phase isolated ACDC converter as an example. It should be understood that the isolated ACDC converter can also be single-phase.

The filter circuit in Figure 4 includes three filter capacitors C and three filter inductors L.

The input end of the PFC circuit is connected to the first end of the filter inductor L, the second end of the filter inductor L is connected to the first end of the filter capacitor C, and the second end of the filter capacitor C is connected to the first shielding layer 10 .

The working principle of the isolated ACDC converter provided by the embodiment of the present application will be introduced below with reference to FIG. 5 .

Refer to Figure 5, which is an equivalent circuit diagram provided by an embodiment of the present application.

The first capacitor C1 is the coupling capacitance between the primary winding of the transformer and the first shielding layer, which is generally tens of pF. The second level C2 is the coupling capacitance between the first shielding layer and the secondary winding of the transformer. Ld is the equivalent inductance of the PFC filter, and Cd is the equivalent capacitance of the PFC filter, generally at the uF level. The PFC filter mainly filters out differential mode signals. Therefore, Ld can be called a differential mode inductor and Cd can be called a differential mode capacitor.

Vd is the interference source generated by the PFC circuit. According to the principle of voltage division, the voltage division of the interference source Vd between points A and B is very low. If Ld is not considered, the difference between uF level Cd and tens of pF level C1 is five orders of magnitude. , it can be seen that the voltage component of the interference source leaked from the isolated ACDC converter is only one hundred thousandth of the original interference source, which reduces the interference of the interference source on the secondary side of the transformer. At the same time, because C1 is a pF-level capacitor, the interference current generated by Vd in the loop is suppressed, suppressing the risk caused by excessive interference current.

The second end of the first shielding layer 10 in Figure 4 is connected to the capacitor of the PFC filter. In addition, the first shielding layer can also be directly connected to one of the phase lines of the AC input.

Refer to Figure 6, which is a schematic diagram of another isolated ACDC converter provided by an embodiment of the present application.

The difference between Figure 6 and Figure 4 is that the location where the second end of the first shielding layer 10 is connected is different.

The PFC filter includes filter capacitor C and filter inductor L;

The input end of the PFC circuit is connected to the first end of the filter inductor L, the second end of the filter inductor L is connected to the first end of the filter capacitor C, and the second end of the filter inductor L is connected to the first shielding layer 10 .

The first shielding layer in Figure 4 and Figure 6 introduced in the above embodiments can both reduce the interference caused by the interference source to the secondary circuit of the transformer. In both cases, the second end of the first shielding layer can be connected to a static point, that is, to allow interference The source is brought back to the static point, thereby reducing the current that interferes with the loop and protecting circuit components. Just connect one end of the first shielding layer to the PFC filter or the input end of the PFC filter.

In addition, in order to suppress the interference caused by the primary switch tube of the DCDC circuit, the embodiment of the present application can also add a second shielding layer to the transformer, which will be described in detail below with reference to the accompanying drawings.

Refer to Figure 7, which is a schematic diagram of yet another isolated ACDC converter provided by an embodiment of the present application.

The isolated ACDC converter provided in this embodiment also includes: a second shielding layer 20;

The second shielding layer 20 is disposed between the primary winding and the first shielding layer 10. The second shielding layer 20 is connected to the DC bus of the DCDC circuit. The second shielding layer 20 is used to suppress the interference signal of the primary switch tube of the DCDC circuit.

The embodiment of the present application does not specifically limit the material of the second shielding layer 20. For example, the material of the second shielding layer 20 may be the same as the first shielding layer.

Specifically, in one possible implementation, the second end of the second shielding layer 20 can be connected to the negative end of the DC bus of the DCDC circuit, that is, when the interference signal generated by the switching tube in the DCDC circuit is directed back to the DC bus of the input end of the DCDC circuit. . It should be understood that the first shielding layer 10 can also isolate the interference of the primary winding of the DCDC circuit on the secondary winding to a certain extent, that is, suppress the interference signal of the primary winding of the DCDC circuit in the primary winding loop. However, this embodiment adds a second The shielding layer 20 can better reduce the interference signal generated by the primary switch tube of the DCDC circuit, reduce the number of devices affected by the interference signal and the surrounding area, and further reduce the interference signal of the isolated ACDC converter.

In addition, in order to suppress the impact of the isolated DCDC circuit secondary side switch on the primary winding of the transformer, the embodiment of the present application can add a third shielding layer and connect the third shielding layer to a certain point of the output capacitor of the secondary winding of the transformer. The third shielding layer is located between the secondary winding and the first shielding layer.

Refer to Figure 8, which is a schematic diagram of another isolated ACDC converter provided by an embodiment of the present application.

The isolated ACDC converter provided in this embodiment also includes: a third shielding layer 30;

The third shielding layer 30 is disposed between the secondary winding and the first shielding layer 10. The third shielding layer 30 is connected to one end of the output capacitor of the DCDC circuit, that is, to the output end of the rectifier connected to the secondary winding of the transformer in the DCDC circuit. In Figure 8, the negative output terminal of the rectifier is connected as an example. Since the output capacitor is connected to the output terminal of the rectifier, the second end of the third shielding layer 30 is also connected to one end of the output capacitor, and the negative output terminal of the rectifier is also a static point. , introducing the interference signal into the static point can effectively reduce the impact of the rectifier tube in the rectifier on the primary winding of the transformer.

Figure 8 only illustrates the combined use of the first shielding layer 10 and the third shielding layer 30. It should be understood that the three shielding layers can be used in combination. See Figure 9, which is another example provided by the embodiment of the present application. Schematic diagram of an isolated ACDC converter.

Figure 9 shows the joint use of the first shielding layer 10, the second shielding layer 20 and the third shielding layer 30, which can not only shield the interference of the PFC filter, but also shield the interference and side effects of the primary switch tube of the DCDC circuit. Interference from edge switch tube.

The above embodiments of the present application are introduced with the PFC circuit as a half-bridge circuit. In addition, the PFC circuit can also be other forms of circuits, and is not limited to a two-level circuit or a three-level circuit.

Refer to Figure 10, which shows a three-level PFC circuit. The four switching transistors Q1-Q4 in Figure 10 are all controllable switching transistors. It should be understood that Q1 and Q4 can also be diodes. The circuit shown in Figure 10 is an I-type, and it can also be a T-type three-level circuit. See Figure 11. Figure 11 includes four controllable switching tubes. It should be understood that Q1 and Q2 can be replaced with diodes. In addition, the PFC circuit can also be a circuit as shown in Figure 12.

Based on the isolated ACDC converter provided in the above embodiments, embodiments of the present application also provide a charging device, which will be described in detail below with reference to the accompanying drawings.

Refer to Figure 13, which is a schematic diagram of a charging device provided by an embodiment of the present application.

The charging equipment 1000 provided in this embodiment includes any of the isolated ACDC converters 2000 introduced in the above embodiments; it also includes: a controller 3000;

Controller 3000 is used to control the output end of the isolated ACDC converter to charge electrical equipment.

Since the charging equipment provided by the embodiments of the present application can better shield interference signals, it can provide higher quality power to the load.

For example, the charging device can be a charging pile or a vehicle charger. When the charging equipment is a charging pile, the input is AC and the output is DC, which is used to charge electric vehicles.

When the charging device is a car charger, it can charge the car while driving, such as a bus or tram.

The embodiments of this application are not specifically limited. The input voltage of the charging device can be selected according to the needs of the actual scene, and the specific number of phases is not limited. It can be single-phase or three-phase.

Refer to Figure 14, which is a schematic diagram of a power supply system provided by an embodiment of the present application.

The embodiment of the present application also provides a power supply system 1100, which includes any of the isolated ACDC converters 2000 introduced in the above embodiments; and also includes: a controller 3000;

The controller 3000 is used to control the output end of the isolated ACDC converter to supply power to electrical equipment.

For example, the electrical equipment can be the load of the computer room, such as the computer room air conditioner, the server in the computer room, or the load of the digital center, etc. The electrical equipment may also be communication equipment.

Since the power supply system provided by the embodiment of the present application can better shield interference signals, it can provide higher quality power to the load.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be practiced in other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

An isolated ACDC converter, characterized by including: a PFC filter, a PFC circuit and a DCDC circuit;

The input end of the PFC filter is used to connect to alternating current;

The input end of the PFC circuit is connected to the output end of the PFC filter;

The output end of the PFC circuit is connected to the input end of the DCDC circuit;

The DCDC circuit includes a transformer, and the transformer includes: a primary winding, a secondary winding and a first shielding layer;

The first shielding layer is disposed between the primary winding and the secondary winding. The first shielding layer is connected to the PFC filter to form a common mode loop and blocks interference signals from being transmitted to the secondary winding. winding.
The isolated ACDC converter according to claim 1, wherein the PFC filter includes a filter capacitor and a filter inductor;

The input end of the PFC circuit is connected to the first end of the filter inductor, the second end of the filter inductor is connected to the first end of the filter capacitor, and the second end of the filter capacitor is connected to the first shielding layer .
The isolated ACDC converter according to claim 1, wherein the PFC filter includes a filter capacitor and a filter inductor;

The input end of the PFC circuit is connected to the first end of the filter inductor, the second end of the filter inductor is connected to the first end of the filter capacitor, and the second end of the filter inductor is connected to the first shielding layer .
The isolated ACDC converter according to any one of claims 1-3, further comprising: a second shielding layer;

The second shielding layer is disposed between the primary winding and the first shielding layer, the second shielding layer is connected to the DC bus of the DCDC circuit, and the second shielding layer is used to suppress the DCDC The interference signal of the switch tube of the primary winding of the circuit.
The isolated ACDC converter according to any one of claims 1 to 4, further comprising: a third shielding layer;

The third shielding layer is disposed between the secondary winding and the first shielding layer, and the third shielding layer is connected to one end of the output capacitor of the DCDC circuit.
The isolated ACDC converter according to any one of claims 1 to 5, characterized in that the first shielding layer is a copper foil located between the primary winding and the secondary winding, and the copper One end of the foil is connected to the PFC filter via an electrical connection wire.
The isolated ACDC converter according to any one of claims 1 to 5, characterized in that the isolated ACDC converter is a three-phase converter or a single-phase converter.
The isolated ACDC converter according to any one of claims 1 to 7, characterized in that the input end of the PFC circuit is used to connect three-phase alternating current, and the PFC circuit includes a three-level circuit or a two-level circuit. ;

The DCDC circuit includes a DCAC inverter bridge, a transformer and an ACDC rectifier bridge; the input end of the DCAC inverter bridge is connected to the output end of the PFC circuit, and the primary winding of the transformer is connected to the output of the DCAC inverter bridge. terminal, and the secondary winding of the transformer is connected to the input terminal of the ACDC rectifier bridge.
A charging equipment, characterized by comprising the isolated ACDC converter according to any one of claims 1-8; further comprising: a controller;

The controller is used to control the output end of the isolated ACDC converter to charge electrical equipment.
A power supply system, characterized by comprising the isolated ACDC converter according to any one of claims 1-8; further comprising: a controller;

The controller is used to control the output end of the isolated ACDC converter to supply power to electrical equipment.